The problem sometimes arises that sporadically occurring pulses need to be detected, whose amplitude, frequency and, in some instances, duration provide useful information. An example of this is a multi-path detection circuit, as used in radios, which supplies irregularly occurring needle pulses, whose amplitude, duration, and frequency serve as an index for the magnitude of the interference resulting from the reception of direct and reflected transmission signals. The situation is similar for a detection circuit used for interferences from an adjacent channel (side-to-side crosstalk). The pulses of interest occur regularly as pulse-shaped breaks in the useful signal level. Thus, the pulses of interest are evaluated as negative pulses, but they can also be evaluated as positive pulses. These pulses are analyzed as measured variables using a microprocessor, which, because of its other tasks, is not able to poll the relevant input signal much more frequently than, for instance, every 10 ms. Therefore, it does not make sense to read the instantaneous values of the input signal into the microprocessor. Because of the short duration of the pulses, even a mean value generation, which would be easier to implement using digital signals, does not provide useful information.